1. Field of the Invention
The invention relates to a crusher unit that can be transported directly on roadways. More particularly, it relates to such a unit in which the crusher is mounted on an elongated, rigid frame, which is supported by several travel mechanisms or support trestles which rest directly on the ground underneath. It especially relates to such a unit in which the frame has several lift jacks which are adjustable in height and lift the frame off the travel mechanisms or support trestles from the ground when extended.
2. The Prior Art
Crusher units are used to treat construction debris directly on site when roads are broken up or buildings are demolished. The crusher can produce reusable materials, e.g. granulates as an additive for concrete or bituminous road surfaces.
For road work, mobile crusher units are known which have frames that are equipped with a complete travel mechanism with wheels. These travel mechanisms can move the units on the construction site, as well as directly on roadways. These wheel mechanisms are very complicated and must be licensed for use on public roadways. However, such wheel mechanisms are not very well suited for construction sites with very uneven ground.
For uneven surfaces, mobile crusher units equipped with heavy caterpillar mechanism are generally used, according to the state of the art. However, such mobile crushers, which are also used in quarries or strip mining operations, have to be loaded onto suitable transport vehicles that can be driven on roadways, for example flat-bed trucks or roll-off trucks. This creates a problem in that the crusher unit with the caterpillar mechanism is relatively high, so that roadways with limited height allowances cannot be used.
Finally, according to the state of the art, so-called semi-mobile crusher units are also known. In these units the frame rests upon rigid support trestles, for example skid trestles while in use at the site. These crusher units are placed on a suitable transport vehicle for transport on roadways by means of a heavy crane.
With all the crusher units of the type discussed above, it is important to align the frame in a precisely horizontal position during operation of the crusher. Otherwise the heavy, rotating parts of the crusher unit will put undue stress on the bearings. For this reason, the known crusher units are equipped with adjustable lift jacks which lift the travel mechanisms or support trestles from the ground. This allows the frame to be horizontally aligned, even when the ground is uneven. Suitable wedges can be placed under the travel mechanisms or support trestles until the frame is in a precisely horizontal position.